Telegraph system, open morse telegraph key alarm circuit



INVENTOR FH HA/VLEV fwd A r TORNE v May 30, 1939. F. H. HANLEY TELEGRAPH SYSTEM, OPEN MOESE TELEGRAPH KEY ALARM CIRCUIT Filed Dec. 21, 1957 Patented May 30, 1939 UNITED STATES PATENT OFFICE TELEGRAPH SYSTEM, OPEN MORSE TELE- GRAPH KEY ALARM CIRCUIT Application December 21, 1937, Serial No. 181,045

7 Claims.

This invention relates to Morse telegraph systems and more particularly to an alarm circuit associated with a Morse telegraph key.

An object of this invention is to provide facilities for signaling a local Morse telegraph station that the telegraph key thereat has inadvertently been left open so that the key may be closed and service resumed.

As is generally known in the operation of the usual Morse telegraph loop circuits, it is necessary that the telegraph key contacts be closed in order to operate the station sounder, as the sounder is in series with the key contacts. If the key is left open, the electrical circuit path through the sounder is broken and it is impossible to call the station. Under such circumstances it has been necessary to inform the station operator of the condition by some supplementary means, such as by using a second telegraph circuit or a telephone if these facilities are available. During the interval that the key remains open, the telegraph loop circuit associated therewith is not operable. Since, in many instances, the loop circuit is continued through more than one local station, the open telegraph key at any station so arranged puts all stations connected to the same loop out of operation. This aggravates the difficulty as it is necessary first to locate the particular station at which the key is open before the key can be closed and service resumed.

According to the present invention a shunt path comprising a condenser is permanently connected around the telegraph key contacts. Positive and negative telegraph battery is supplied to the loop on periodic reversals from a common circuit at a central telegraph station to which the loop is connected. The reversed current pulses are passed through the shunt around the open contact to vibrate the station sounder as a signal to the station operator that the telegraph key is open and the operator thereupon restores the key.

A feature of this invention is that a shunt path comprising a condenser is utilized to pass current, the polarity of which is periodically reversed, around the open contacts of a telegraph key to operate a device responsive to such current as a signal to close the key.

A further feature of this invention is that a spark killer device, used to suppress sparking at the telegraph key contacts, which device comprises a condenser, is used as the shunt path for the signaling current.

A further feature of this invention is that facilities are provided for indicating to the teleaph central station operator that the open tele- H multiple jacks so distributed through the centraltelegraph station that they are readily available to all the telegraph loop circuits terminating at said central station.

Reference to the signal figure on the accompanying drawing and the following description discloses the operation of this invention.

In the single figure the wiring shown to the right of plug l2! including'the dotted lines indicate a telegraph subscribers loop circuit. The apparatus at the right, comprising the telegraph key [22, the sounder I23, the resistance I24 and the condenser I25 in series with resistance in, both shunting key I22 contacts, is located at the telegraph subscribers station. All of the rest of the apparatus and wiring is located at the telegraph central oifice to which the subscribers loop circuit is connected. Jacks H2, H3, us, H5 and H6 are test jacks with a series circuit from battery to ground through their contacts. I 09 and HI indicate jack outlets of an interposition trunk circuit which is multipled through the various' operators positions of the telegraph test board at the central station. I05 is a relay and I0! is a polar relay. Illl is a motor which drives interrupter arm I04 across the segments of interrupter I63. Ground N12 is furnished to alternate segments of the outer interrupter ring. When these segments engage with the outer brush, ground is furnished through an internal connection in the interrupter arm I84, to the inner ring of interrupter I93 to which a conductor to the lower winding of polar relay It! is connected. The speed of motor IUI is such that ground is interrupted by an open 23 times per second. I26 and 521 are three conductor plugs. The -tip conductors only of plugs H6 and I21 are interconnected by conductor I28. H1 is a three-conductor plug whose tip and sleeve conductors are interconnected by leads which in- 'clude the meter H8, key H9 and sounder I20. The function of this and all other apparatus will now be described in detail.

When the attendant is unable to communicate with a particular telegraph subscriber and suspects that the trouble is due to an open telegraph key at the subscribers station, the attendant connects plug l2! into jack H5, plug H7 into jack H3 and plug l2 6 into jack Ill. Plug I2! is inserted into jack H2 and removed intermit tently. When plug I26 is inserted in jack III, the ring of the jack is actuated downward and a circuit is closed from ground through relay I05 winding, through the lower armature actuated by the ring, through the make contact associated with the ring lower armature, through resistance H0 to negative battery. Relay I05 is operated. The operation of relay I05 closes motor IOI circuit at relay I05 right-hand make contact, operating the motor. The operation of relay I05 also closes a circuit from negative battery through resistance I06, left-hand contact, lower winding polar relay I01, to the inner ring of interrupter I03, inner brush of interrupter arm I04, outer brush of interrupter arm I04, to the alternate grounded and open segments of interrupter I03. When a grounded segment engages with the outer brush a circuit is closed to ground I02. Relay I01 is so arranged that when current flows through its bottom winding the relay is operated so that its armature engages the contact to which is connected negative battery. When the interrupter arm is on an open segment and the circult to ground I02 is broken, relay I01 is operated so that its armature engages the contact to which is connected positive battery. Relay I01 is fast enough to follow the 23-cycle interruptions.

When the armature of relay I01 is in engagement with the right-hand contact, a circuit may be traced from negative battery, relay I01 righthand contact, relay I01 armature, tip of jack HI, tip of plug I26, conductor I28, tip of plug I21, tip of jack H2, tip of jack H3, tip of plug H1, meter H8, key H9, winding of sounder I20, sleeve of plug H1, sleeve of jack H3, tip and break contact of jack H4, tip of jack I I5, tip of plug I2 I, through the subscribers upper loop conductor, through the shunt comprising resistance I24 and condenser I25 around the open contacts of key I22, through the winding of sounder I23, through the lower conductor of the subscribers loop, sleeve of jack H5, tip of jack H6, make contact of jack H6 to ground. When relay I01 armature is operated to the left-hand contact, positive battery is supplied through the circuit last traced. The 23-cycle positive and negative reversals are passed through the condenser in the shunt path to operate the sounder. The operator inserts plug I21 into jack I I2 and removes it intermittently to interrupt the sounder signal. The operator at the telegraph subscribers station is instructed to close the key in response to the vibrating sounder signal. The closing of the key is indicated by the movement of the needle due to increased current through the loop when the closed key short-circuits the shunt path through the resistance and condenser. When the meter indicates that the key at the subscribers station has been closed, plugs I2I, H1, I26 and I21 are removed and the circuit is restored to its original condition.

Only one subscribers station is shown connected to the subscribers loop. It is understood that more than one station circuit may be connected to the loop. As arranged herein, positive and negative -volt battery is connected alternately to the armature of relay I01 while the other end of the circuit is connected to ground at the make contact of jack H6. As thus connected it has been found that with a mf. condenser and a SOD-ohm resistance the circuit operates efiectively with loops up to 12 miles. With a slight rearrangement readily possible to one skilled in the art, namely, with positive and negative 130-volt battery oppositely poled at each end of the circuit, the circuit will operate effectively with loops up to 24 miles.

What is claimed is:

1. In a telegraph system, a polar relay, an armature and a pair of contacts thereon, batteries of opposed polarities connected between ground and each of said contacts, a series circuit extending from said armature through a telegraph loop circuit including a shunt around the open contacts of a telegraph key and a station sounder to ground and means for operating said armature to engage said contacts alternate- 1y to operate said sounder as an alarm to indicate that said key contacts are open.

2. A telegraph system according to claim 1, a meter in said circuit to indicate that said open contacts have been closed.

3. A telegraph system according to claim 1 wherein the means for operating said armature includes a transmitter-distributor connected to a winding of said polar relay.

4. In a telegraph system, a central switching station, a local telegraph station, a telegraph loop connecting said stations, a telegraph key, a pair of cooperating contacts normally closed when said key is idle on said key, an electrical circuit comprising a condenser shunting said contacts and a telegraph sounder, said key, condenser and sounder all connected to said loop at said local station, a plurality of operators positions at said central station, a circuit for supplying alternate pulsations of positive and negative electromotive force common to said positions, individual outlets in said common circuit at each of said positions and flexible means comprising jacks and plugs also at each of said positions for interconnecting one of said outlets and said loop to operate said sounder when said key is inadvertently left open.

5. In a telegraph system, a central switching station, a plurality of operators positions thereat, a signal supply circuit common to said positions, outlets connected to said supply circuit individual to said positions, a telegraph subscribers station circuit, a telegraph line circuit connecting said station circuit to said central station, a telegraph key with contacts inadvertently open at said subscribers station, a shunt path comprising a resistance and a condenser around said contacts, a telegraph sounder in series with said contacts in said line circuit, a series jack circuit also at said central station, means for flexibly interconnecting said supply circuit to said station circuit through said series jack circuit, to operate said sounder when said key is open, and meter means at said central station for indicating that said key has been closed.

6. In a telegraph switching system, a central switching station, a signal supply circuit, a series jack circuit and a meter circuit thereat, a local telegraph station circuit, a telegraph key, contacts on said key inadvertently open, a condenser shunting said contacts, and a telegraph sounder all in said local station circuit, means for connecting said supply circuit, said jack circuit, said meter circuit and said station circuit all in series, means in said connected circuit for operating said sounder as a signal to close said key and to indicate on said meter that said key has been closed.

7. In a telegraph system, a transmitter-distributor, a polar relay, an armature thereon, a neutral relay, a first jack, a second, third, and fourth jack, a telegraph loop, a station circuit in said loop, a telegraph key with a pair of contacts thereon, and a sounder in said station circuit, a shunt including a condenser around said key contacts, a meter, means for establishing a series circuit including said armature, all of said jacks, said loop and said meter and means including said neutral relay and said transmitter-distributor for impressing alternate pulses of opposed battery on said armature through said condenser to operate said sounder when said contacts are open and to indicate on said meter when said contacts are closed.

FRANK H. HANLEY. 

